Creating selection and applying processing to selected areas only

[tnkumar]

In photoshop, you can use various tools like lasso, rectangle, magic wand to select sections of the image and applying processing to the selected area only.
I see that there is the concept of a mask in pixinsight, but how do I select specific areas in the mask.

[Nocturnal]

The short answer is : you're not supposed to process that way. Arbitrary selection of areas to process leads to fake images. Might as well paint them instead of capture them.

The longer answer is: use math (PI processes) to define your mask and then use that to limit your processing to certain areas of the image. For saturation enhancement I generally extract a Lightness frame, modify it with the histogram process and then apply it before using curves. This way my curves are applied only to bright areas. The reason this is better than lassoing is that you can describe your processing in mathematical terms rather than arbitrary ones.

Clearly this is a topic of some controversy and debate but it's THE defining difference between the photshop and pixinsight camps.

[tnkumar]

If you use Noel Carboni's Gradient Xterminator with photoshop, typically, the DSO is deselected and the Xterminator applied to the rest of the image.
What is the suggestion from Pixinsight on the area to select?
Also, any suggestion on what tool does the job similar to Gradient Xterminator?

[Nocturnal]

Use Dynamic Background Extraction. There are video tutorials on how to use this tool.

[tnkumar]

DBE was really nice.
What is the equivalent of Noel Carboni's Local Contrast Enhancement tool in PixInsight?

[Nocturnal]

I have no idea. You may want to search the forums or use google. I'm sure someone else has run into this before.

[tnkumar]

More info on LCE http://www.prodigitalsoftware.com/Astronomy_Tools_For_Full_Version.html
and attached is a picture of what it achieves

[pfile]

http://pixinsight.com/doc/tools/LocalHistogramEqualization/LocalHistogramEqualization.html